Such support structures for motor vehicles are generally built into side pieces of the body or in automobile doors so as to afford better side impact protection and better protect the vehicle passengers in the event of a side impact on the vehicle. Such support structures must be dimensioned so that they provide the greatest possible moment of resistance to bending, since it is known that such structural parts used in car body side pieces or automobile doors are much more heavily strained by bending than by tension during an accident. Namely, such structural parts are secured by their ends to the car body or the doors, so that upon impact from the outside such support structures act like a two-point beam in regard to the distribution of the forces and stresses acting from the outside. Hence, the bending stress in the middle region of the support structure is substantially greater than in the two end regions. In the case of a side impact, the support structure may collapse, but it then acts as a tie bar, so that impact energy is dissipated in the further course of the side impact under deformation of the attached body piece or door frame and the best possible protection is achieved for the vehicle passengers.
Such a support structure is known from DE 44 25 572A1. In the structural part shown there, the above-mentioned mechanical properties are achieved in that in a deformation section, which is arranged between a first and a second connecting section, the deformation section is provided in its lengthwise dimension with a recess formed from a middle web and legs connected to it by connecting regions, and an additional reinforcement element is installed in the recess.
Although with the structural part of DE 44 25 572A1 the safety of the passengers can be heightened as compared to structural parts without an additional reinforcement element, the use of the additional reinforcement element causes a weight increase, which results in a high fuel consumption and thus a more negative environmental balance of the motor vehicle.